Apparatus for submarine signaling



Sept. 10, 1946.

Sept w, 1946.

E. E. TURNER, JR 247329 APPARATUS FOR SUBMARINE SIGNALING 5 Sheets-Sheet2 Filed July 22, 1939 Sep. 1, 1946. TURNER.JR 2,407329 APPARATUS FORSUBMARINE S IGNALING Filed July 22, 1959 5 Sheets-Sheet 3 INVENTOR. EvwwE.TURNEF2 d2.

Patented Sept. 10, 1946 APPARATUS FOR SUBMARINE SIGNALING Edwin E.Turner, Jr. West Roxbury, Mass. as-

signor, by mesne assignments, to Submarine Sigma! Company, Boston,Mass., a corporation of Delaware Applicaticn July 22, 1939, Serial No.285,910

2 Claims. (Cl. 177-386) The present invention relates to translatingdevices for converting compressional wave energy to electrioal energyand vice versa. More partieularly, the present invention relates to suchdevices as used for signaling u-nder water and is particularly concernedwith the transmission and reception of compressional wave energy in abeam.

It has heretofore generally been understood that if a vibratable pistonbe made large in its dimensons in oomparison with the wave length of thecompressional waves at the signaling frequency, a concentration ofenergy along the axis perpendicular to the radiating surface will beobtained. I-Iowever, such a concentration of energy in a main beam isaccompanied by smaller concentrations of energy in directons at variousangles with the axis of the main beam.

When the relative acoustic energy intensities in space in the freemedium as produced by such a device are plctted with respect to theseveral angular directions from the aXis perpendicular to the radiatingsurface as om polar coordinate graph paper, the main concentration ofener y will appear as a large lobe representing the main neem, and aplurality of auxiliary lobes or ears representing the subsidary energyconcentrations in directions other than that of the main beam will alsoappear. These auxilary lobes of the energy distribution pattern areoften objectionable particularly or signaling under water as in acousticranging for the determination of the dstance and direction of remoteobjects. Such subsidiary energy concentrations can be reduced by notdriving the plane radiating surfac'e as a piston but by driving it atvarying amplitudes over its surface. A suitable amplitude distributionfor this purpose will be shown below, but the present invention isprimarily concerned with arrangements for obtaining any desiredvibrational amplitude distribution of th radiating surface.

It should be noted that the characteristics referred to herein asapplying to a compressional wave producing device also apply when thesame device is used for receiving such waves.

The invention will best be understood by the following description takenwith reference to the accompanying drawings in which Fig. 1 is a polardiagram of representative compressonal wave energy distributions; Fig. 2is a graph showing a suitable radiating surface amplitude distributionfor the production of one of the energy distributions shown in Fig. 1;Fig. 3 shows diagramniatically a cross section of a magnetostrictionoscillator for producing compressional wave energy; Fig. 4 is a sectionof the same device along the line IVIV in Fig. 3; Fig. 5 representsdiagrammatically a cross section of an electrodynamic oscillator; Fig. 6is a cross section of the device of Fig. 5 taken along the line VIVI;Figs. 7 and 8 are schematc diagrams showi-ng arrangements oreiectrically connecting the driving elements of the devices shown inFigs. 3 to 5; Fig. 9 is a vertical cross section of an electromagneticoscillator simlar to that shown in Fig. 5 but modified in accordancewith a modification of the present invention; Fig. 19 is a verticalcross section of another modification of such an electrodynamicoscillator; Fig 11 isa schematic diagram of an arrangement foxelectrically operating the devices of Figs. 3 to 5; Fig. 12 is avertica1 section of a further modification of an electrodynamicoscillator; Fig. 13 is a horizontal section of the device of Fig. 12taken along the line XIII-XIII; Fig. 14 is a vertical section of a stil]further modification of an electrodynamic oscillator; and Fig. 15 is ahorizontal section of the device of Fig. 14 taken along the line XV-XV.

As shown in Fig. 1, the energy distribution produced in a free medium bya representative extended, continuous, finite, plane radiating surfacehaving a dimension greater than the wave length at the signalingfrequency vibratng as a piston has a maximum energy concentration alongan axis y perpendicular to the radiating surface. At small angles fromthe axis y the energy decreases as indicated by the dotted line 60. Atsome larger angle from the axis 1 the radiated energy will fal1 to zeroand at a still greater angle agan build up to a lower but stillsignificant maximum va1ue; then again fall to zero as the angle isfurther increased, and so on throughout the hemsphere facing theradiating piston. 'Ihus, there will appear successve lobes of energyconcentration at varous angular distances from the axis y as indicatedin Fig. 1 by the lobes e1, e2 and es. If the piston be circular, it willbe understood that these subsidiary lobes are in the form of hollowcones, the graph in Fig. 1 indicating merely the energy distribution inone plane.

A more desirable energy distribution pattern can be obtained byeffectively varying the amplitude over the radiating surface from theedges to the center so that the greatest amplitud will occur at thecenter. If, for example, the vibrational amplitude be vared as shown inFig. 2,

3 the energy distribution represented by the solid curve in Fig. 1 canbe obtained.

In Fig. 2 the linear amplitude of the radiating surface is indicated bythe ordinates which represent the ratio Ar/AO representing the ratio ofthe amplitude at any radial coordinate measured from the center of theradiating surface to the amplitude at the center, so that the maximumamplitude is indicated as unity. Radial distances from the center of theradiating surface are indicated by the abscssae which specificallyrepresent the ratio r/a, where 1 is the radial distance from the centerat any poi-nt and a is the total radius of the radiating surface. Theparticular amplitude distribution curve shown in this figure follows theequation:

The amplitude distribution shown in Fig. 2 produces an energydistribution in the medium as shown by the solid curve in Fig. 1. Thmain lobe E has somewhat greater width than the main lobe en produced byuniform amplitude of the vibrating surface but the auxiliary lobes E1,E2 and E3 are very much reduced in intensity.

T0 produce such a desired energy distribution or any other desiredenergy distrbution it is necessary to cause the radiating surface tovibrate with varying amplitudes over its surface when energy is beingtransmitted and conversely to cause the surface to produce electricalresponse which varies in a similar marmer when receiving. Two arrangements for accomplishing this with devices of the type shown inFigs. 3 to 6 are shown in Figs. 7 and 8.

Figs. 3 and 4 show a magnetostriction oscillator having a radiatingelement adapted by its outcr surface to contact a signaling medium.'I'his is driven by a plurality of tubes or rods 2 of magnetostrictivematerial firmly fixed to the element i at one end and free to vibrate atthe other end. These tubes may be arranged over the inner surface of theelement I in any convenient manner but preferably are fairly uniformlyspaced and they may be arranged in concentric circles as shown in Fig.4. Per clearness only a relatively small number of tubes is shownalthough in practice it is not uncommon to use many hundredg D tubes.Each of the tubes together with its prooortion of the element I forms ahalf wave length vibrating system with the node preferably locatedslightly above the inner surface of the element l. Elach tube issurrounded by an electromagnetic :oil 3 to which electrical energy ofthe proper fre- :1uency is supplied for magnetostrictively setting thetubes and thereby the radiating surface into vibration or conversely forgenerating electrical energy when the radiating surface and the tubesare vibrated by compressional wave energy. An ascillator of this type isdescribed in more detail .n my copending application Serial No. 677,179,led June 23, 1933.

Another form of oscillator is shown in Figs. 3 and 6. An element 4having a radiating surace in contact with the signaling medium has aalurality of concentric rings of electrically zonductive materialmounted on its inner surface. our such rings are shown in the dravvingsalhough more may be used if desired. A magnetic eld is produced acrosseach of the rings 5 by neans of an electromagnet E5 having a plurality)f concentric poles extending between the rings and excited by directcurrent polarizing coils E.

Wound en or embedded in the outside surfaces of the concentric poles arealternating current windings 8 to which energy is supplied at theignaling frequency. The rings 5 are proportioned to have a height suchthat together with their iespective portions of the element 4, they willeach form a half wave length vibrating system at the signalingfrequency. The entire system will, therefore, be set into vibration whenthe coils 8 are energized and conversely will generate an electromotiveforce in the coils 8 when the system is vibrated by compressional waves.An electrodynamic oscillato-r of this type is described in greaterdetail in m copending application Serial No. 24,078, filed May 29, 1935.

When all the coils of the magnetostriction oscillator shown in Figs. 3and 4 or all the driving coils of the electrodynarnic oscillator shownin Figs. 5 and 6 are excited with alternating current of the sameamplitude and phase, the respective radiating surfaces will vibrate witha uniform amplitude over the entire surface and thereby will produce anenergy distribution in the medium as indicated by the dotted curve inFig. 1. Conversely if all the coils are connected to actuate anindicating device in a uniform manner, the device as a receiver willhave a sensitivity in the various directions as indicated by the samedotted curve in Fig. 1.

T0 produce a different energy or sensitivity distribution I vary theampere-turns of alternating current excitation of the coils associatedwith the driving elements over the area of the radiating element, or Iprovide diierent loadings of the driving elements, that is I vary themass ratio between the mass of the driving elements and their respectiveassociated proportions of mass of the radiating element.

The variation in ampere-turns can be accom plished in two ways, namelyby varying the turns in the several coils and exciting all of them withthe same current or by giving all the coil the same number of turns butdifferent current excita tion or by a, combination of varying number ofturns and diierent current values. The two undamental arrangements areshown in Figs. 7 and 8.

In Fig. 7 the elements 9, 10, 11 and 12 indicate respectively thealternating current coils 8 for the four rings of the electrodynamicoscillator of Figs. 5 and 6 or the four circular groups of coils 2 ofthe magnetostriction oscillator shown in Figs. 3 and 4 with theindividual coil of each circular group connected together in series. Thegrouping of the coils need not necessarily be circular, for this dependsentirely upon the amplitude distribution and the beam pattern which itis desired to obtain.

With the magnetostricton oscillator the individual coils in each groupare given the same number of turns but the coils for the differentgroups are given different numbers of turns, the group at the centerhaving the largest number of turns. Similarly with the electrodynamicoscillater the coil for the innermost ring is given the greatest numberof turns, the other coils beinggiven successively smaller numbers ofturns. In both cases the variation in the number of turns from thecenter toward the edge of the device is made to conform as nearly aspossible to the desired amplitude distribution, for exarnple, inaccordance with Equation 1 given above. The elements 9, lil, H and I2constituted as just clescribed are connected in series and then across asuitable source of alternating current b;; m ans 5 of the leads l3 andI4, condensers I5 and [6 interposed when necessary to prevent directcurrent from passing into the alternating current line and for powerfactor correction.

In the magnetostriction oscillator direct polarizng current is usuallypassed through the same coils as the alternating current. Since thecoils in the varicus groups have different number of turns, theapplication of the direct current potential across all the groupsconnected in series would nt provide the same ampere-turns of polarizingflux for all the magnetostrictive elements. To provide for this, apotentiometer I 1 is connected across a sourc of direct potential andthe several groups of coils are provided with successively larger directpotentials to make the polarizing ampere-turns in each group the same.This is accomplished by means of the common lead [8 and thepotentiomet-er sliding contacts l@ 20, 2! and 22. In each of these leadschokes 23 are provided to avoid alternating current from passing throughthe potentiometer. For the sup p1y of polarizing current in this manner,the switches ll must, of course, be closed.

For the electrodynamic oscillator or for the magnetostriction oscillatorin the case where separate polarizing coils are provided the polarizingcoils may, of course, simply all be given the same number of turns andsuitalc-le groups supplied in series or in parallel from a single directcurrent source whereby the polarizing flux in all the elements will bethe same.

Any desired variation of ampere-turns can also be obtained by themodification shown in Fig. 8. In this case the elements 9, lil, H and !2constituted as described with reference te Fig. 7 are all given the samenumber of turns. Alternating potential of the proper requency issupplied to the primary 2 of a transformer 25 having a tapped secondary25. The elements 9 to I2 are connected in series. one end of thecombination being connected to one terminal of the secondary 26 and thejunction between the elements 9 to I2 being connected to the severaltaps as by the leads 21, 28, 2e and 3il. The taps on the secondary 26are adjusted so that the various elements 9 to l2 will be supplied withvoltages varying in accordance vvith the desired amplitude distribution,for example, that according to Equation 1 above. Since all the elements9 to [2 in this case have the same number of turns, they may be suppliedwith polarizing current from a single source of direct current throughchoke coils 3! by closing the swtches 5. The condensers 63 preventdirect current from passing through the transformer winding 26. Since thelements 9 to l2 are all connected in series, they will all receive thesame polarizing flux.

Another arrangement for preducing desired amplitude variations over theradiating surface consists in varying the mass ratios of the severaldriving elements. Fig. 9 shows electrodynamic driving elements but itwill be understood that magnetostrictive elements may similarly be usedif desired. The electrodynamic elements 5 are similar to those shown inFig. 5 and in horizontal section would appear as in Fig. 6. Likewise,the alternating current coils 8 and the polarizing coils are similar tothese shown in Fig. 5. The alternating current coils as well as thepolarizing coils are connectecl electrically to have uniform excitationand to produce uniform eleztrical response when vibrated. However, theinner surface 32 of the radiating element 33 is made dishshaped. By thismeans the outermost ring is associated with a much larger mass than isthe innermost ring. A11 the rings, however, are tuned to the samefrequency and the length of the several rings consequently varies.Therefore, the rnass ratio varies between the successive rings wherebyuniform exctation of the driving coils will produce a varying amplitudedistribution of the radiating surface. Thus any desired amplitudedistribution can be obtainecl simply by making the surface 32 of adifferent shape to con form with the particular distribution desired.

The mass ratio between the various driving elements of the radiatingsurface can also be varied by the arrangement shown in Fig. 10. In thiscase the radiating element 3 l has its inner surface divided by narrowcircular slots into a plurality of rings 3%, 37, 38 and 39, each drivenby one or more electrodynamic elements 5 which may be the same as theseshown in Fig. 5 and in horizontal section would appear as in Fig. 6. Theoutermost portion 35 of the radiating member is made the thickest. Theother elements 31, 35 and 39 progressively decrease in thickness, thethinnest element-being at thecenter. The mass associated withthe severaldriving elements 5 is therefore varied in a manner similar to that ofFig. 9, whereby with uniform excitation of the rings the radiatingsurface will vibrate at varying amplitude, the greatest amplitude beingat the center. In this case, also, it will be understood thatmagnetostrictive driving elements can be substituted for theelectrodynamic elements shown.

A further arrangement for obtaining a desi red amplitude distributionover the radiating surface by variation of the mass ratios of theseveral driving elements is shown in Figs. 12 and 13. In this case theelectromagnetic driving rings, of which four are shown, nuznbered 55,56, 51 and 58, are made of successively drninishing thickness, thethickest ring loeing placed near the center. As in the othermodificatons the rings are all tuned to the same frequency having regardto the respective prop0rtions of mass of the radiating element 59 whichis associated with each. Each ring, therefore, together With itsproportion of the element 59 forms a one-half wave length system at thesignaling frequency. Since the ring at the center is thickel than theother rings, the ratio of its mass with respect to the portion of themass of element 59 associated with it is smaller than the correspondingmass ratio for the other rings. The central portion of the radiatingelement 59 will therefore be driven at a greater amplitude, and theamplitude will gradually decrease toward the edges or successivelydecreasing ring thicknesses as shown. It will be evident from what hasbeen said With reference to the other modifications that the variationsin the thickness of the successive rings can be made to bring about anydesired amplitude distribution over the radiating surface. It will alsobe evident that the same arrangement can be applied wheremagnetostrictive driving elements are employed. In this case the tubesor rode near the center of the diaphragm will be made thickest andsucces sively thinner elements will be used at points out from thecenter to conform to any desired radiating surface amplitudedistribution A still further modification or obtaining varying massratios is shown in Figs. 14 and 15. In this modification the drivingrings 5 are again all of uniform thickness but are spaced differentdistances apart so that the several rings are associated with more orless of the massand.

surface area of the radiatng eiement here numbered E9. Where a largeamplitude at the center of the radiating surface is desired, the drivingelements are spaced most c1oseiy at the center as shown. Since all thedriving elements are supplied with the same power, those at the centerbeing required to move the 1east radiating surface area, w1l drive thelatter with the greatest amplitude. In this maner any desired amplitudedistribution aan readily be obtained. Where magnetostrictive drivingelements are employed, they, too, of course, will be spaced closetogether at these areas of the radiating member where the greatestamplitude is desired.

When using apparatus of the type just described for echo Iangingpurposes it may be advantageous for the purpose of reducing straysigna1s and. reverberations to a minimum to use one energy distributionpattern for transmission of the initial impulse and to use a diierentenergy distribution pattern for receiVing the echo. This is readilyaccomplished with the devices shown in Figs. 3 and 5, particularly Whenal] the coi1s are given the same number of turns and the ampere-turnsvariation is obtained by varying the voltage applied to the severalgroups of coils. Fig. 11 shows an e1ectric operating circuit for thispurpose. Here the elements 9, lil, II and !2 representing the coi1sassociated With the several rings of an electrodynamic oscillator 01representing successive groups of series connected ci1s of amagnetostriction oscillator are connected to the tapped winding 26 of atransformer 25 through the contacts of a three-pole relay 40 having anoperating coil 4I. The latter is arranged to be energized from a batteryor other current source 42 through the upper contact 43 of a sending key44. When the key is not depressed, contact 43 will be closed and relaycoil 4l energized whereby re1ay contacts 54 wi1l a11 be closed. In thiscondition which is for receiving the elements 9 to I?. are eachconnected to appropriate portions of the winding 26 to produce aresultant response in the other winding 24 of the transformer inaccordance with any desired energy distribution pattern preferably thatdefined by Equation 1. The winding 24 of the transformer 25 is at thistime connected through the contacts 48, 52 of a double-pole,double-throw re1ay 47 to a receiving amplifier 53 which may be connectedto any desired indicating device.

When the key 44 is depressed for sending a signa], contact 43 is open,thereby deenergizing re1ay coi1 4! and permitting contact 54 to open.The eiements 9 to |2 are then connected in series and together acrossthe entire winding 26 of transformer 25. Depressing the key 44 a1soc1oses contact 45 energizing the re1ay 0011 46, whereby contacts 43 moveto the right as shown in the drawings and connect with contacts 49. Thetransformer winding 24 is thereby connected to a suitabie source ofalternating potential of the sgnaling frequency. Since the elements to12 are now a11 connected in series, they wi11 be energized equally and,assuming that they have the same numbers of turns, the energydistribution pattern for the transmitted signal w11 be that of a pistonas is represented by the dotted curve in Fig. 1.

By this arrangement it will be noted that the transmtted signal has astrong main beam together with subsidiary maxima at varous angu- 1ardirections to its axis. On receiving, however, the sensitivitydistributon if made in accordance with Equaton 1 wi1l correspond to thesolid curv in Fig. 1. The auxiliary maxima will be seen to be of much1ower intensity in this case and the largest one E1 lies in a directiondifferent rom that of any of the subsidiary maxima of the dotted curve.Consequently energy transmitted in directions other than that. of themain bea after refiection from a distant object or f1om discontinuitiesin the medium, will not be received with apprecable intensity.

The arrangement shown in Fig. 11, therefore, provides a means forchanging from one energy distribution pattern to a diierent energy distribution pattern between sending and receiving. It wi1l ee evident thatthe arrangement shown is net limited to the use of the particular energytributions shown in Fig. 1, but that any other different distributionmay be employed if desireei. It however, particulariy advantageous i thesubsidiary maxima during reception do not c oincide in direction withthe subsidiary maxima obtained during transmission and also When thesubsidiary maxima during reseption are as small as possibie inintensity. This arrangement is aso of especial importance When it isdesired to receive as litt1e energy as possible from directons outsideof the main beam and yet to transmit as much energy as possibie intowater during sending. Since a piston radiating surface has uniformamplitude all over its surface, its cntire surface can be driven at themaximum pessible amplitude, namely that at which cavitation cocurs,whereby the greatest possible amount of energy wil]. be radiated alongthe main axis perpendcuiar to the radiating surface. When soms ot'neramplitude distribution is employed, oniy the area oi maximum amplitudecan be permitted to reach the cavitation limit, while the remainder ofthe surface must vibrate at a 1ower amplitude. This results in adecreased tota1 energy output, and at the same time decreases themaximum energy radiated along the main axis. The use of the arrangementshown in Fig. 11, i1owevcr, makes it possible to radiate maximum total,ene1gy during transmission and yet have the benefits of a specialdistribution pattern dur i1g reception.

Having now described my invention, I claim: 1. A submarine sgnalingdevice having a so1id unitary radiating member having a continuousradiating surface of surface dimensions many tiine the Wave iength ofthe compressional waves in the signaling medium at the signalingfrec;uency, said surface adapted to be in contact with the signalingmedium, said radiating nember havin a reverse surace opposed to 5 1d1rst ce with a plurality of metallic eiastic iongi "d thereon eradiating member, a plur COS operatively assoc' ments ior vibrating tsame, sad e eotric current carrjing coiis p-osuione-zi nearer the centert1e radiating member havng greater ampere-turns magnitude than the coiisoperatively associated with metallic elements nearer the peripnery ofthe radiating member wherehy the adiating areas naar the center of theradiatirig memcer are excited with large ampiitudes than arprogressively rom the een of the ra ting memner or the pur oi red-ucingthe intensity of the secondary 1obes of the beam pattern of thesubmarine sig naiing device.

2. A submarine signaling device having a solid unitary radiating memberhaving a continuous radiating surface of surface dmensions many timesthe wave length of the compressonal waves in the sgnaling medium at thesgnaling frequency, said surface adapted to be in contact with thesignalng medium, said radatn member havng a reverse surface opposed tosad first surface with a pluralty of magnetostrictive longitudinallyvbratable rode mounted thereon substantally extendng over the entreradiating member, a pluralty of electrc current-carrying c01ssurrounding sad tubes for operatively energizng the same, sad electrccurrent-carryng coi1s having connections whereby they are operated ingroups wth respect to ther distance from the center of the radatingmember, the groups of co1s nearer the center of the radiating memberhaving greater ampere-turns magntude than the coil groups progressivelyaway from the center whereby the radatng areas near the center of theradiatng members a.re excted with larger ampltudes than areasprogressvely away from the center of the radating member for the purposeof reducing the ntensty of the secondary lobes of the beam pattern ofthe submarine signalng device.

EDWIN E. TURNER, JR.

